The present invention relates to a thin film magnetic recording head used for recording and reproducing in a magnetic disk drive or the like and a magnetic disk drive mounted therewith.
In a magnetic disk drive, data on a recording medium is read and written by a thin film magnetic head. In order to increase a recording capacity per unit area of a magnetic disk, it is necessary to form an area recording density in a high density. However, according to a current longitudinal recording system, when a length of a bit to be recorded is reduced, there poses a problem that the plane recording density cannot be increased owing to thermal fluctuation of magnetization of a medium.
In order to solve the problem, there is provided a perpendicular recording system for recording a magnetization signal in a direction perpendicular to a medium. Also in the perpendicular recording system, in reproduction, there can be used a magnetoresistance effect type head (MR head) and a giant magnetoresistance effect type head (GMR head) having a large reproduced output. Meanwhile, in recording, it is necessary to use a single pole type magnetic head. Also in perpendicular recording, it is necessary to increase a tracking density and a line recording density in order to increase the recording density. In either of them, in order to increase the tracking density, it is necessary to form a track width of the magnetic head very finely and highly accurately.
Further, in perpendicular recording, there poses a problem that noise is generated by an external magnetic field or the like. For example, there is a description with regard to a spike noise from an external magnetic field in ‘Japanese Patent Application Laid-Open No. H07-225901’. After the noise is detected, the noise is canceled. Further, the problem of noise after recording is also considered to be derived from that a magnetic domain of a main pole is unstable and the magnetic domain is moved. There is a description with regard to a single pole type head having a shield for resistance against external magnetic field in ‘Digest of 24th Conference of Japan Society of Applied Magnetics (P161)’.
According to a proposal of ‘Japanese Patent Application Laid-Open No. H07-225901, there is disclosed means for detecting a spike noise and avoiding error and there is no description with regard to a reduction in the noise at the magnetic head. Further, there poses a problem that a main pole is magnetized by an external magnetic field, a magnetic field thereof is leaked to a medium and the magnetization signal on the medium is erased.
As a countermeasure thereagainst, in ‘Digest of 24th Conference of Japan Society of Applied Magnetics (P161)’, there is disclosed a structure of providing a shield against the external magnetic field in the single pole head. According to the structure, the shield against the external magnetic field is constructed by a structure of being exposed to a surface against the media. Therefore, although there is achieved a significant effect for preventing the external magnetic field from entering the main pole, there also poses a problem that the shield against the external magnetic field collects the external magnetic field, the external magnetic field leaks from the surface against the media to the media, the magnetization signal of the media is erased or a signal is written. Further, there also poses a problem that a magnetic field in recording is leaked from the main pole and leaked to the media via the shield against the external magnetic field.